The present invention relates to a multicylindrical rotary compressor in which a rotation number of a driving element is controlled by control means.
Heretofore, in a mainstream of an air conditioner provided with this type of multicylindrical rotary compressor, a capability of the multicylindrical rotary compressor is controlled by a control unit depending on a capability on a use side (interior heat exchanger). Especially, in recent years, there have been many air conditioners in which a rotation number of the multicylindrical rotary compressor is linearly controlled using an inverter. Accordingly, it is possible to vary the rotation number of the multicylindrical rotary compressor arbitrarily from 0 to a predetermined rotation number.
This multicylindrical rotary compressor, for example, a two-cylinder rotary compressor provided with first and second rotary compression elements is constituted by storing a driving element and the first and second rotary compression elements driven by a rotation shaft of the driving element in a sealed container. The first and second rotary compression elements include: first and second cylinders, first and second rollers engaged with eccentric portions formed on the rotation shaft to rotate eccentrically in the respective cylinders, respectively; and first and second vanes which abut on the first and second rollers to divide each cylinder into low and high pressure chamber sides. The first and second vanes are constantly urged with respect to the first and second rollers by spring members.
Moreover, when the driving element is driven by the control unit, a low-pressure refrigerant gas is sucked into the low-pressure chamber side of the cylinder of each of the first and second rotary compression elements via a suction port, and compressed by the operations of each roller and each vane to constitute the refrigerant gas at high temperature and pressure. After the gas is discharged from the high-pressure chamber side of each cylinder into a discharge sound muffling chamber via a discharge port, the gas is discharged into the sealed container, and discharged to the outside (see, e.g., Japanese Patent Application Laid-Open No. 5-99172).
In such multicylindrical rotary compressor, the rotation number of the multicylindrical rotary compressor is lowered, and the compressor is operated based on an output of an inverter in a small-capacity operation under a light load or by a low-speed rotation. However, a problem has occurred that when the rotation number excessively lowers, an operation efficiency of the driving element drops, a leakage loss increases, and an operation efficiency remarkably drops.